The present invention relates to a synchronous transmission control system for synchronously transmitting data between transmitting and receiving sides and, more particularly, a synchronous transmission control system for data transmission between data processors such as minicomputers or microcomputers.
A synchronous transmission control system commonly used in the field of data communication is operated in such a way that a predetermined synchronous pattern signal is transmitted n times in succession from the transmission side to the receiving side and, upon reception of the synchronous pattern signal, the receiving side takes a synchronization with the synchronous pattern signal and, after the synchronization is completed, the receiving side receives successively the data delivered from the transmission side. One form of the synchronous pattern signals is comprised of a succession of frame pattern signals each consisting of 8 bits or 16 bits. More particularly, in such a data transmission, the receiving side converts the serial data delivered from the transmitting side into the parallel data through the shift register included in the receiving side. In the receiving side, the parallel data converted is successively compared with the synchronous pattern signals which has been predetermined in relation with the time point of data transmission and stored in the synchronous register, the comparison being made by the comparator. When the successive comparison shows coincidence between the respective data and the synchronous pattern signals, the pattern data to be inputted to the shift register from the time of the coincidence is treated as the information data and thus loaded into the data register, with an assumption that the synchronization is established between the transmitting and receiving sides. The data register outputs the information data in parallel fashion.
In the synchronous transmission control system as mentioned above, the synchronous pattern signal is constructed by a single kind of codes so that the synchronization is relatively easily done. However, in case where the synchronous signal is constructed by grouping a plurality of specified pattern codes in sequential fashion, the frame of the synchronous pattern results in an elongation. Therefore, the synchronous pattern signal consisting of many kinds of synchronous pattern codes is unsuitable for the synchronous transmission control system above mentioned. If it should be applied for the synchronous transmission control system, the system constructed is considerably complicated and its manufacturing cost becomes high.